The present invention relates to insulated glass constructions, and more particularly to such constructions wherein a pair of glass sheets are spaced from one another by a spacer frame extending about the periphery of the assembly.
Many insulated glass constructions have been developed to provide thermally efficient window assemblies. The most popular form includes at least two glass sheets and a spacer frame between each pair of sheets to space the sheets from one another. The air between the two sheets reduces thermal flow through the assembly and must be hermetically sealed to prevent moisture penetration which can condense on the interior glass surfaces.
Basically, two processes have been developed for hermetically sealing the glass sheets together and/or to the spacer frame. In a first construction, the glass sheets directly contact the spacer frame, which is recessed from the edges of the glass sheets. An adhesive, such as polysulfide, is applied in the edge recesses adjacent the spacer frames to be flush with the glass edges. However, the polysulfide adhesives do not provide a consistently reliable hermetic seal. Consequently, moisture penetration can occur with the above-noted problems.
In a second construction, butyl or other sealant is extruded onto both faces of the spacer frame before assembly of the glass sheets thereon. The sandwiched assembly is then processed through rollers to produce a unit having the required overall thickness. The butyl sealant does not adhere as strongly as the previously described polysulfide adhesives to the glass sheets. Accordingly, relative slippage between the sheets can result and thereby create seal damage with premature failure of the unit. Slippage problems are exacerbated when the units must be transported and/or handled substantially prior to installation within a final frame or product. This is particularly true with door lights which are typically assembled at a first location, transported from the first location to a second location, partially disassembled, and then installed within a door. Further, the insulated glass is typically supported at its edges by screw bosses within the door light further creating pressure points and possible relative slippage between the glass.